Created
February 10, 2016 14:18
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Test of guava cache stats coherency
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| import java.util.*; | |
| import java.util.concurrent.*; | |
| import com.google.common.cache.Cache; | |
| import com.google.common.cache.CacheBuilder; | |
| import com.google.common.cache.CacheStats; | |
| import static com.google.common.base.Preconditions.checkState; | |
| import static com.google.common.base.Throwables.propagate; | |
| import static java.util.concurrent.Executors.*; | |
| public class CacheTest { | |
| private static final int NUMBER_OF_CACHE_GET = 100; | |
| private static final int THREAD_POOL_SIZE = 6; | |
| private CacheTest() { | |
| } | |
| /** | |
| * Performs NUMBER_OF_CACHE_GET for the same key on a cache then verifies that cache stats are coherent | |
| */ | |
| public static void main(String[] args) { | |
| for (int j = 0; j < 200000; j++) { // several runs may be necessary to reproduce the pb | |
| final Object key = new Object(); | |
| final Object value = new Object(); | |
| final Callable<Object> valueLoader = new Callable<Object>() { | |
| @Override | |
| public Object call() throws Exception { | |
| return value; | |
| } | |
| }; | |
| final Cache<Object, Object> cache = CacheBuilder.newBuilder().maximumSize(100).recordStats().build(); | |
| try { | |
| ExecutorService pool = newFixedThreadPool(THREAD_POOL_SIZE); | |
| final Collection<Callable<Void>> executions = new ArrayList<>(); | |
| for (int i = 0; i < NUMBER_OF_CACHE_GET; i++) { | |
| executions.add(new Callable<Void>() { | |
| @Override | |
| public Void call() throws Exception { | |
| cache.get(key, valueLoader); | |
| return null; | |
| } | |
| }); | |
| } | |
| List<Future<Void>> futures = pool.invokeAll(executions); | |
| try { | |
| for (Future<Void> future : futures) { | |
| try { | |
| future.get(); | |
| } catch (Exception e) { | |
| throw propagate(e.getCause()); | |
| } | |
| } | |
| CacheStats stats = cache.stats(); | |
| /* OK */ | |
| checkState(stats.loadCount() == 1, "Unexpected load count : %s", stats.loadCount()); | |
| /* OK */ | |
| checkState(stats.evictionCount() == 0, "Unexpected eviction count : %s > 0", stats.evictionCount()); | |
| /* OK */ | |
| checkState(stats.hitCount() == (NUMBER_OF_CACHE_GET - stats.missCount()), // since eviction count is 0 | |
| "Inconsistent counters : gets(%) != hits(%s) + miss(%s)", // | |
| NUMBER_OF_CACHE_GET, stats.hitCount(), stats.missCount()); | |
| /* regularly NOK */ | |
| checkState(stats.missCount() <= THREAD_POOL_SIZE, "Unexpected miss count : %s > nb of threads (%s)", stats.missCount(), THREAD_POOL_SIZE); | |
| } finally { | |
| pool.shutdown(); | |
| } | |
| } catch (Throwable e) { | |
| System.out.println("Run " + j); | |
| System.out.println("Cache stats " + cache.stats()); | |
| throw propagate(e); | |
| } | |
| } | |
| } | |
| } |
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